Within Portland’s boundaries there are approximately 247 parks and green spaces 12,591 acres. Located in the NE neighborhoods of Portland, 16.7 acres of that green space is designated as Alberta Park. An count of the trees of Alberta park was taken by the tree inventory project which is a formation of the local neighborhood and volunteers. A full count of all other species was taken from the virtual tour on a document provided by Portland Parks and Recreation entitled Trees of Alberta Park, which was used as a main resource to determine the ratios of native and non natives. In terms of diversity the park has many different species present, 65% of present species named are non-native. However, natives make up the majority biomass, according to their counts, Douglas Fir (Pseudotsuga menziesii), makes up for 72% of the population of trees. A visual count taken from the virtual tour, and an in person visit since the actual list of trees was not listed, nor were the actual population tolls, or data sets provided. According to my count, there are 172 Doug Firs (72%) present, and all other species population numbers individually do not breach 1%.
Douglas Fir (Pseudotsuga menziesii) is clearly the main focus of this park, being a specialized native species for this region. Due to urban sprawl and development, these very large trees cannot be planted near streets or sidewalks but can be found in sporadic back yards or larger green spaces in between zoning of buildings (Park blocks downtown). This limitation results in many parks within Portland’s urban boundaries large native trees like Douglas Firs are focused on.
As mentioned, size is the most distinguishing feature of these specimens, reaching between 70 – 330 feet tall and up to 6 ft in diameter. Distribution covers a large swath of the North West of the North American continent, from Canada to Utah to the pacific coast, and a large range of elevations. The giant’s house many small native species that rely on its presence for habitat, such as the spotted owls and red tree voles. Both species are under near threatened conservation status, and the presence of these trees is crucial for their status’ not to increase in severity. Other small ferns, fungi, sap sucking insects and moths also utilize Doug Firs as well.
All other natives tree species at the park made up 0.05 percent of the stand, only 1 or 2 of each in the space. Overall these trees were generally larger than the non-natives, most being pines and firs compared to Birches and Oaks.
Another great feature of Alberta park is its Ecologically Sustainable Landscape, one of many across Portland’s parks and rec. locations. Within a shady dour fir stand an acre of land was fitted with 3000 plus native plants. Created by Parks and Rec. and volunteers, these features serve as an effective understory for birds, insects and other small fauna that use these species as food or habitat. Since all plants in these patches are native, ratios to non native wasn’t obtainable, but a general plant list was produced by parks and rec. Species with the highest plant counts were; Dear fern (828), Sword fern (828), False sunflower (728), Blanket Flower (728), Fringe Cup (567), Oxalis (567). Non-natives and invasive plants are thankfully not a general concern due to the regular upkeep and maintenance of the park by staff and volunteers.
Sources
Blake, Alison. “Portland Parks.” Http://Depts.washington.edu/, depts.washington.edu/open2100/Resources/1_OpenSpaceSystems/Open_Space_Systems/portland.pdf.
Portland Parks and Rec. “The State of Portland Parks” http://www.portlandoregon.gov, https://www.portlandoregon.gov/parks/article/89433
Portland Parks and Rec. “Trees of Alberta Park”, http://www.portlandoregon.gov, https://pdx.maps.arcgis.com/apps/MapJournal/index.html?appid=8b9926722bf24dd5bc3bebc13ec45a11#
Seeing Trees PDX 